This invention relates to albums for containing photographs and other sheet materials such as collectible cards, and in particular to such albums having covers and leaves of thermoplastic materials that are weld-incompatible, and to the process for fabricating such albums.
A popular type of photograph album includes an album cover comprising or covered with a thermoplastic material, and further includes a plurality of sleeved leaves or pages of a clear thermoplastic material. The cover and the leaves may be of the same type of thermoplastic material, for example vinyl (polyvinyl chloride or PVC) cover and leaf material, or polypropylene cover and leaf material, and the fabrication process includes heat welding the leaves to the spine of the album cover by conventional thermoplastic welding processes.
Vinyl is a versatile material for use as album covers; for example, vinyl adapts to various decorating and embossing techniques for creating a variety of surface textures and aesthetic effects. However, vinyl is generally considered to have certain limitations in its utilization as a material for sleeved leaves for containing photographs or collectible cards. For utilization as album leaves, polypropylene has certain advantages over vinyl. Polypropylene is substantially chemically inert and will generally not react with dyes and other surface components of photographs and collectible cards, and is physically resistant to extreme heat and cold. Unlike vinyl, polypropylene is highly suitable for archival applications, and polypropylene leaves having pockets for containing photographs or cards are particularly suitable for the long-term storage of such contents.
Although vinyl sheets can be heat welded to other vinyl sheets, and polypropylene sheets can be heat welded to other polypropylene sheets, vinyl and polypropylene are incompatible materials for being heat welded to one another; i.e. polypropylene sheet material cannot reliably be thermally welded to vinyl sheet material.